Add new, from scratch implementation of hsearch() et al that actually works.

Obtained from:	NetBSD
MFC after:	1 month

3 files changed, 394 insertions, 3 deletions

diff --git a/lib/libc/stdlib/Makefile.inc b/lib/libc/stdlib/Makefile.inc
index c2f42df..9a96360 100644
--- a/lib/libc/stdlib/Makefile.inc
+++ b/lib/libc/stdlib/Makefile.inc
@@ -5,8 +5,8 @@
 .PATH: ${.CURDIR}/../libc/${MACHINE_ARCH}/stdlib ${.CURDIR}/../libc/stdlib
 
 MISRCS+=abort.c abs.c atexit.c atof.c atoi.c atol.c bsearch.c calloc.c div.c \
-	exit.c getenv.c getopt.c getsubopt.c heapsort.c labs.c ldiv.c \
-	malloc.c merge.c putenv.c qsort.c radixsort.c rand.c random.c \
+	exit.c getenv.c getopt.c getsubopt.c hcreate.c heapsort.c labs.c \
+	ldiv.c malloc.c merge.c putenv.c qsort.c radixsort.c rand.c random.c \
 	reallocf.c realpath.c setenv.c strhash.c strtol.c strtoll.c strtoq.c \
 	strtoul.c strtoull.c strtouq.c system.c tdelete.c tfind.c tsearch.c \
 	twalk.c
@@ -25,11 +25,12 @@ SRCS+=	strtod.c
 
 .if ${LIB} == "c"
 MAN+=	abort.3 abs.3 alloca.3 atexit.3 atof.3 atoi.3 atol.3 bsearch.3 \
-	div.3 exit.3 getenv.3 getopt.3 getsubopt.3 labs.3 \
+	div.3 exit.3 getenv.3 getopt.3 getsubopt.3 hcreate.3 labs.3 \
 	ldiv.3 malloc.3 memory.3 qsort.3 radixsort.3 rand.3 random.3 \
 	realpath.3 strtod.3 strtol.3 strtoul.3 system.3 tsearch.3
 
 MLINKS+=getenv.3 putenv.3 getenv.3 setenv.3 getenv.3 unsetenv.3
+MLINKS+=hcreate.3 hdestroy.3 hcreate.3 hsearch.3
 MLINKS+=qsort.3 heapsort.3 qsort.3 mergesort.3
 MLINKS+=rand.3 rand_r.3 rand.3 srand.3 rand.3 sranddev.3
 MLINKS+=random.3 initstate.3 random.3 setstate.3 random.3 srandom.3 \
diff --git a/lib/libc/stdlib/hcreate.3 b/lib/libc/stdlib/hcreate.3
new file mode 100644
index 0000000..1500b2a
--- /dev/null
+++ b/lib/libc/stdlib/hcreate.3
@@ -0,0 +1,206 @@
+.\" $FreeBSD$
+.\"
+.Dd May 8, 2001
+.Os
+.Dt HCREATE 3
+.Sh NAME
+.Nm hcreate , hdestroy , hsearch
+.Nd manage hash search table
+.Sh LIBRARY
+.Lb libc
+.Sh SYNOPSIS
+.In search.h
+.Ft int
+.Fn hcreate "size_t nel"
+.Ft void
+.Fn hdestroy void
+.Ft ENTRY *
+.Fn hsearch "ENTRY item" "ACTION action"
+.Sh DESCRIPTION
+The
+.Fn hcreate ,
+.Fn hdestroy ,
+and
+.Fn hsearch
+functions manage hash search tables.
+.Pp
+The
+.Fn hcreate
+function allocates sufficient space for the table, and the application should
+ensure it is called before
+.Fn hsearch
+is used.
+The
+.Fa nel
+argument is an estimate of the maximum
+number of entries that the table should contain.
+This number may be adjusted upward by the
+algorithm in order to obtain certain mathematically favorable circumstances.
+.Pp
+The
+.Fn hdestroy
+function disposes of the search table, and may be followed by another call to
+.Fn hcreate .
+After the call to
+.Fn hdestroy ,
+the data can no longer be considered accessible.
+.Pp
+The
+.Fn hsearch
+function is a hash-table search routine.
+It returns a pointer into a hash table
+indicating the location at which an entry can be found.
+The
+.Fa item
+argument is a structure of type
+.Vt ENTRY
+(defined in the
+.Aq Pa search.h
+header) containing two pointers:
+.Fa item.key
+points to the comparison key (a
+.Vt "char *" ) ,
+and
+.Fa item.data
+(a
+.Vt "void *" )
+points to any other data to be associated with
+that key.
+The comparison function used by
+.Fn hsearch
+is
+.Xr strcmp 3 .
+The
+.Fa action
+argument is a
+member of an enumeration type
+.Vt ACTION
+indicating the disposition of the entry if it cannot be
+found in the table.
+.Dv ENTER
+indicates that the
+.Fa item
+should be inserted in the table at an
+appropriate point.
+.Dv FIND
+indicates that no entry should be made.
+Unsuccessful resolution is
+indicated by the return of a
+.Dv NULL
+pointer.
+.Sh RETURN VALUES
+The
+.Fn hcreate
+function returns 0 if it cannot allocate sufficient space for the table;
+otherwise, it returns non-zero.
+.Pp
+The
+.Fn hdestroy
+function does not return a value.
+.Pp
+The
+.Fn hsearch
+function returns a
+.Dv NULL
+pointer if either the
+.Fa action
+is
+.Dv FIND
+and the
+.Fa item
+could not be found or the
+.Fa action
+is
+.Dv ENTER
+and the table is full.
+.Sh ERRORS
+The
+.Fn hcreate
+and
+.Fn hsearch
+functions may fail if:
+.Bl -tag -width Er
+.It Bq Er ENOMEM
+Insufficient storage space is available.
+.El
+.Sh EXAMPLES
+The following example reads in strings followed by two numbers
+and stores them in a hash table, discarding duplicates.
+It then reads in strings and finds the matching entry in the hash
+table and prints it out.
+.Bd -literal
+#include <stdio.h>
+#include <search.h>
+#include <string.h>
+
+struct info {			/* This is the info stored in the table */
+	int age, room;		/* other than the key. */
+};
+
+#define NUM_EMPL	5000	/* # of elements in search table. */
+
+int
+main(void)
+{
+	char string_space[NUM_EMPL*20]; /* Space to store strings. */
+	struct info info_space[NUM_EMPL]; /* Space to store employee info. */
+	char *str_ptr = string_space; /* Next space in string_space. */
+	struct info *info_ptr = info_space; /* Next space in info_space. */
+	ENTRY item;
+	ENTRY *found_item; /* Name to look for in table. */
+	char name_to_find[30];
+	int i = 0;
+
+	/* Create table; no error checking is performed. */
+	(void) hcreate(NUM_EMPL);
+
+	while (scanf("%s%d%d", str_ptr, &info_ptr->age,
+	    &info_ptr->room) != EOF && i++ < NUM_EMPL) {
+		/* Put information in structure, and structure in item. */
+		item.key = str_ptr;
+		item.data = info_ptr;
+		str_ptr += strlen(str_ptr) + 1;
+		info_ptr++;
+		/* Put item into table. */
+		(void) hsearch(item, ENTER);
+	}
+
+	/* Access table. */
+	item.key = name_to_find;
+	while (scanf("%s", item.key) != EOF) {
+		if ((found_item = hsearch(item, FIND)) != NULL) {
+			/* If item is in the table. */
+			(void)printf("found %s, age = %d, room = %d\n",
+			    found_item->key,
+			    ((struct info *)found_item->data)->age,
+			    ((struct info *)found_item->data)->room);
+		} else
+			(void)printf("no such employee %s\n", name_to_find);
+	}
+	return 0;
+}
+.Ed
+.Sh SEE ALSO
+.Xr bsearch 3 ,
+.Xr lsearch 3 ,
+.Xr malloc 3 ,
+.Xr strcmp 3 ,
+.Xr tsearch 3
+.Sh STANDARDS
+The
+.Fn hcreate ,
+.Fn hdestroy ,
+and
+.Fn hsearch
+functions conform to
+.St -xpg4.2 .
+.Sh HISTORY
+The
+.Fn hcreate ,
+.Fn hdestroy ,
+and
+.Fn hsearch
+functions first appeared in
+.At V .
+.Sh BUGS
+The interface permits the use of only one hash table at a time.
diff --git a/lib/libc/stdlib/hcreate.c b/lib/libc/stdlib/hcreate.c
new file mode 100644
index 0000000..ecc2431
--- /dev/null
+++ b/lib/libc/stdlib/hcreate.c
@@ -0,0 +1,184 @@
+/* $NetBSD: hcreate.c,v 1.2 2001/02/19 21:26:04 ross Exp $ */
+/* $FreeBSD$ */
+
+/*
+ * Copyright (c) 2001 Christopher G. Demetriou
+ * All rights reserved.
+ * 
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *          This product includes software developed for the
+ *          NetBSD Project.  See http://www.netbsd.org/ for
+ *          information about NetBSD.
+ * 4. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ * 
+ * <<Id: LICENSE,v 1.2 2000/06/14 15:57:33 cgd Exp>>
+ */
+
+/*
+ * hcreate() / hsearch() / hdestroy()
+ *
+ * SysV/XPG4 hash table functions.
+ *
+ * Implementation done based on NetBSD manual page and Solaris manual page,
+ * plus my own personal experience about how they're supposed to work.
+ *
+ * I tried to look at Knuth (as cited by the Solaris manual page), but
+ * nobody had a copy in the office, so...
+ */
+
+#include <sys/cdefs.h>
+#if defined(LIBC_SCCS) && !defined(lint)
+__RCSID("$NetBSD: hcreate.c,v 1.2 2001/02/19 21:26:04 ross Exp $");
+#endif /* LIBC_SCCS and not lint */
+
+#include <sys/types.h>
+#include <sys/queue.h>
+#include <errno.h>
+#include <search.h>
+#include <stdlib.h>
+#include <string.h>
+#include "namespace.h"
+
+/*
+ * DO NOT MAKE THIS STRUCTURE LARGER THAN 32 BYTES (4 ptrs on 64-bit
+ * ptr machine) without adjusting MAX_BUCKETS_LG2 below.
+ */
+struct internal_entry {
+	SLIST_ENTRY(internal_entry) link;
+	ENTRY ent;
+};
+SLIST_HEAD(internal_head, internal_entry);
+
+#define	MIN_BUCKETS_LG2	4
+#define	MIN_BUCKETS	(1 << MIN_BUCKETS_LG2)
+
+/*
+ * max * sizeof internal_entry must fit into size_t.
+ * assumes internal_entry is <= 32 (2^5) bytes.
+ */
+#define	MAX_BUCKETS_LG2	(sizeof (size_t) * 8 - 1 - 5)
+#define	MAX_BUCKETS	((size_t)1 << MAX_BUCKETS_LG2)
+
+/* Default hash function, from db/hash/hash_func.c */
+extern u_int32_t (*__default_hash)(const void *, size_t);
+
+static struct internal_head *htable;
+static size_t htablesize;
+
+int
+hcreate(size_t nel)
+{
+	size_t idx;
+	unsigned int p2;
+
+	/* Make sure this this isn't called when a table already exists. */
+	if (htable != NULL) {
+		errno = EINVAL;
+		return 0;
+	}
+
+	/* If nel is too small, make it min sized. */
+	if (nel < MIN_BUCKETS)
+		nel = MIN_BUCKETS;
+
+	/* If it's too large, cap it. */
+	if (nel > MAX_BUCKETS)
+		nel = MAX_BUCKETS;
+
+	/* If it's is not a power of two in size, round up. */
+	if ((nel & (nel - 1)) != 0) {
+		for (p2 = 0; nel != 0; p2++)
+			nel >>= 1;
+		nel = 1 << p2;
+	}
+	
+	/* Allocate the table. */
+	htablesize = nel;
+	htable = malloc(htablesize * sizeof htable[0]);
+	if (htable == NULL) {
+		errno = ENOMEM;
+		return 0;
+	}
+
+	/* Initialize it. */
+	for (idx = 0; idx < htablesize; idx++)
+		SLIST_INIT(&htable[idx]);
+
+	return 1;
+}
+
+void
+hdestroy(void)
+{
+	struct internal_entry *ie;
+	size_t idx;
+
+	if (htable == NULL)
+		return;
+
+	for (idx = 0; idx < htablesize; idx++) {
+		while (!SLIST_EMPTY(&htable[idx])) {
+			ie = SLIST_FIRST(&htable[idx]);
+			SLIST_REMOVE_HEAD(&htable[idx], link);
+			free(ie->ent.key);
+			free(ie);
+		}
+	}
+	free(htable);
+	htable = NULL;
+}
+
+ENTRY *
+hsearch(ENTRY item, ACTION action)
+{
+	struct internal_head *head;
+	struct internal_entry *ie;
+	uint32_t hashval;
+	size_t len;
+
+	len = strlen(item.key);
+	hashval = (*__default_hash)(item.key, len);
+
+	head = &htable[hashval & (htablesize - 1)];
+	ie = SLIST_FIRST(head);
+	while (ie != NULL) {
+		if (strcmp(ie->ent.key, item.key) == 0)
+			break;
+		ie = SLIST_NEXT(ie, link);
+	}
+
+	if (ie != NULL)
+		return &ie->ent;
+	else if (action == FIND)
+		return NULL;
+
+	ie = malloc(sizeof *ie);
+	if (ie == NULL)
+		return NULL;
+	ie->ent.key = item.key;
+	ie->ent.data = item.data;
+
+	SLIST_INSERT_HEAD(head, ie, link);
+	return &ie->ent;
+}